2025/2026: Complete Exam-Style Questions with Detailed Rationales
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Examination Instructions
● Time Allowed: 75 minutes
● Total Questions: 50
● Question Formats: Multiple Choice, Select All That Apply (SATA), Data
Interpretation, and Case-Based Scenarios
● Materials Permitted: Non-programmable scientific calculator; periodic table
(provided)
● Scoring: Each question is worth 2 points. SATA questions are worth 2 points only
if all correct options are selected with no incorrect options selected.
● Directions: Read each question carefully. For SATA questions, select all options
that apply. For all other questions, select the single best answer.
Section I: Multiple Choice Questions (Questions 1–25)
1. A researcher hypothesizes that increasing soil nitrogen will increase plant growth.
She sets up three groups: Group A receives standard fertilizer, Group B receives
high-nitrogen fertilizer, and Group C receives no fertilizer. All other variables are held
constant. What is the independent variable in this experiment?
,A) Plant growth rate measured in centimeters
B) The amount of nitrogen in the fertilizer
C) The type of soil used in each pot
D) The amount of water given to each group daily
Correct Answer: B
Rationale: The independent variable is the factor deliberately manipulated by the
researcher. In this experiment, the amount of nitrogen is varied across groups, while
plant growth rate (A) is the dependent variable being measured.
2. A graduate student observes that pond water samples collected near agricultural
runoff have significantly lower dissolved oxygen than samples from undisturbed ponds.
In the context of the scientific method, this observation represents which step?
A) Hypothesis formulation
B) Data collection and observation
C) Controlled experimental design
D) Peer review and publication
,Correct Answer: B
Rationale: Recording measurable differences in dissolved oxygen between sample sites
constitutes data collection and observation, which typically precedes hypothesis
formation and experimental testing.
3. Which property of water allows insects such as water striders to walk on the surface
of a pond without breaking through?
A) High specific heat capacity
B) Cohesion and surface tension
C) Adhesion to glass and plant surfaces
D) Universal solvent properties
Correct Answer: B
Rationale: Cohesion between water molecules creates surface tension, a force strong
enough at the air-water interface to support small organisms. Specific heat (A) and
adhesion (C) are important water properties but do not explain this phenomenon.
, 4. A buffer system in human blood normally maintains pH at approximately 7.4. A
patient presents with a blood pH of 7.2. Which statement accurately describes this
finding?
A) The blood is slightly more alkaline than normal
B) The blood has a lower hydrogen ion concentration than normal
C) The blood is more acidic than normal, with a higher H⁺ concentration
D) The buffer system has completely failed and is nonfunctional
Correct Answer: C
Rationale: pH is inversely related to hydrogen ion concentration. A decrease from 7.4 to
7.2 indicates increased acidity (higher [H⁺]). The buffer is overwhelmed but not
necessarily nonfunctional (D).
5. A biochemist is analyzing the primary structure of a newly discovered protein. She
notices that two cysteine residues, initially far apart in the linear amino acid sequence,
are brought into close proximity during folding and form a covalent bond that stabilizes
the tertiary structure. What type of bond has formed?
A) Hydrogen bond
B) Ionic bond